What happens in a black hole?

Popular theory says you get crushed and stay in the middle until the end of the universe, because the gravity is too strong.

Conservation of energy and mass says you can't stay inside. So, what if you come out the other side instead, into a mirror image of the universe?

Sure, you'll be in millions of little pieces (I prefer to call them atoms), but that's neither here nor there. You'll eventually form part of a star, then planets, then life. That's how the (current) universe began, after all. A massive explosion from a tiny point in space-time.

What if the big bang was only a little bang, and the universe had recently collapsed in on itself, only to release the massive amount of energy and mass stored by the collapse?

On the other side of the black hole, light would travel in the opposite direction. Electrons would spin in the opposite direction. In fact, this would explain why nothing detectable happens on the other side – because we're in a different phase shift.

I think that explains dark matter too.

Incidentally, the space-time thing is silly. Time is relative to the space in which it resides. If you split the two, black holes make sense. From the known universe to its constituent atoms, as a mirror image of itself all the way down, separating time and space is necessary. Each level is another "dimension".

For the record, I'm just as much a black hole expert as anyone else. No one has ever been able to study one close up, so it's all speculation. This is my take on it.